Design and Simulation of Adsorption Citrus Picking Actuator

Yiwei Zhang, Lifeng Wang

and Qiang Luo

College of Mechanical Engineering, Chongqing Three Gorges University, Chongqing, China

Keywords: Adsorption Type, Citrus, End Actuator, Simulation Analysis.

Abstract: In order to realize mechanized citrus picking, an adsorption type non-destructive citrus picking end effector

was designed based on the basic characteristics of citrus, which is mainly composed of three parts: shearing

mechanism, adsorption mechanism and transmission frame. The three-dimensional model of the end effector

is established, and its kinematics simulation and finite element simulation analysis are carried out to ensure

the rationality of the mechanism design and material selection. The simulation results show that the structure

design and motion characteristics of the end effector are reasonable, which can basically meet the needs of

citrus picking.

1 INTRODUCTION

Citrus is one of the pillar industries of agriculture in

the hilly areas of southwest China. At present, it has

become an important supporting industry for

Chengdu Chongqing Economic Circle to build a

characteristic and efficient agricultural system.

However, the level of agricultural mechanization in

hilly areas is low, and the cost of manual picking

accounts for more than 30% of the total cost of citrus.

In addition, with the serious problems of

industrialization development and population aging in

China, citrus picking costs will further increase, so

agricultural mechanization in hilly and mountainous

areas is imminent (Zhang, 2019; He, 2018; Li, 2008).

Experts and scholars at home and abroad have

carried out more in-depth research on automatic fruit

and vegetable picking machinery, among which Johan

Baeten, Davidson, etc. have analyzed apple machine

picking and designed corresponding picking actuators

(Baeten, 2008; Monta, 1998); In addition, Han Shukui

(Han, 2019) Liu Yue (Liu, 2014), Xu Liming (Xu,

2018), Yang Wenliang (Yang, 2019) , Zeng Wen

(Zeng, 2019) and others have studied the citrus

picking problem and its picking actuator. Among

them, a hairdresser pusher picking end actuator from

Kubota (Kubota, 2009), Japan, a picking robot based

on snake like swallowing principle from Fu Shun (Fu,

2017), and an underactuated three finger picking end

actuator from Wu Jijun (Wu, 2018) are very

representative.

At present, the main problems of citrus picking

robot are long picking time, low efficiency and high

damage rate. Therefore, this paper designs an end

effector for the non-destructive harvesting of ancient

red tangerine, and uses the finite element method to

carry out simulation analysis.

2 STRUCTURE DESIGN OF

ADSORPTION END EFFECTOR

2.1 Basic Physical Characteristics of

Citrus

Randomly select 100 ancient red oranges and ponkan

oranges with different shapes and sizes, measure the

transverse diameter, longitudinal diameter and fruit

stem diameter of ancient red oranges and ponkan

oranges with vernier calipers, and count the largest

and smallest fruit stem diameter, and the transverse

diameter and longitudinal diameter of oranges. Use

the electronic scale to measure their mass and count

the maximum mass and minimum mass. After

measurement, the average weight of the ancient red

orange is 88g, the average transverse diameter is

53mm, the average longitudinal diameter is 45mm,

and the average diameter of the fruit stalk is 2.1mm.

Zhang, Y., Wang, L. and Luo, Q.

Design and Simulation of Adsorption Citrus Picking Actuator.

DOI: 10.5220/0012142500003562

In Proceedings of the 1st International Conference on Data Processing, Control and Simulation (ICDPCS 2023), pages 28-33

ISBN: 978-989-758-675-0

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

Table 1: Measurement results of parameters of Citrus.

aramete

maximu

minimu

avera

quality（g） 127 62 88

Transverse diameter（mm） 65 46 53

longitudinal diameter（mm） 58 36 45

diameter of the fruit stalk（mm） 2.5 1.7 2.1

Figure 1: Separation experiment of citrus fruit and stem.

2.2 Basic Mechanical Properties of

Citrus

Take 50 oranges, connect the hook of the

dynamometer with the fruit stem of the citrus through

an inelastic rope, and slowly pull the tension meter at

a constant speed until the fruit stem and the fruit are

separated. The maximum force required to separate

the fruit from the peduncle is 46.2N, and the

minimum force is 21.9N.

Cut the fruit stem by simply supported beam and

measure the required shear force (as shown in Table

2), and the maximum cutting resistance required is

79.2N.

2.3 Structure Design of Adsorption

Citrus end Effector

In combination with the above citrus related

parameters, an adsorption type citrus non-destructive

picking end actuator is designed as shown in Figure

2, which is composed of three parts: a shearing

mechanism, an adsorption mechanism and a

transmission frame.

Figure 2: Three-dimensional model of adsorption end-

effector.

Table 2: Experimental data of fruit stem cutting.

diameter

of the

fruit stalk

)

maximum

cutting

resistance(N)

diameter o

the fruit

stalk(mm)

maximum

cutting

resistance(N)

1.9 47.5 2.1 71.3

3.0 77.8 2.1 59.8

2.3 67.9 3 79.2

2.4 56.4 2.8 63.5

2.5 63.5 2.1 67.3

2.8 62.8 2 72.5

2.7 53.5 2 75.3

2.6 63.3 1.9 53.8

2.9 71.5 2.7 62.6

2.2 66.2 2.0 67.3

Design and Simulation of Adsorption Citrus Picking Actuator

Figure 3: Partial drawing of shearing mechanism.

Figure 4: Parameter setting

2.4 Key Structure Design of Actuator

The shearing mechanism is designed based on the

parallelogram connecting rod mechanism. The piston

rod pulls the parallelogram mechanism to move

symmetrically towards the center, and the blade

moves in parallel with the knife slot to cut the citrus

fruit stalks.

At the moment of shearing by the shearing

mechanism, the angle is about 60°, and the maximum

cutting resistance of citrus is 79.2N. Calculate the

tensile force F according to Figure 3.

=2 137NFF≈

Combined with the actual environment, the

pneumatic double rod cylinder TN16.10 with a

0.5MPa air pressure pull of 150.8N is selected as the

cylinder in the shear mechanism.

3 FINITE ELEMENT

SIMULATION ANALYSIS OF

END ACTUATOR

3.1 Dynamic Simulation Analysis of

end Actuator

Use Adams software to carry out kinematics

simulation, create constraints and define the material

property as high manganese steel 7.98×10

-3

g/m3,

2.06×10

N/mm

, Poisson's ratio 0.26; Steel 7.801×10

g/mm3, 2.07×10

N/mm

, Poisson's ratio 0.29. Load

150N tension on the cylinder piston rod to drive the

ICDPCS 2023 - The International Conference on Data Processing, Control and Simulation

(a) (b)

Figure 5: Displacement curve of blade in X and Y direction.

(a) (b)

Figure 6: Velocity and acceleration curve of blade in X and Y direction.

Table 3: Material Properties.

material density（g/mm

） Young's modulus（N/mm

） Poisson's ratio

（stem) Branch

0.000438 11000 0.33

（blade）Permanganate steel 0.007980 206000 0.26

（connecting link） steel 0.007801 207000 0.29

（connecting link）pla 0.00121 3000 0.35

shear mechanism to move, and finally obtain the force,

speed and acceleration curves in the movement

process.

According to the analysis of the displacement,

speed and acceleration of the blade, the maximum

distance of the blade moving in the X direction is

about 70mm, the maximum distance in the Y direction

is about 7mm, and the maximum distance of the

cylinder in the Y direction is 10mm; Under the tension

of 150N, the speed and acceleration of the blade are

smooth curves without obvious instantaneous impact,

so the mechanism of the picking end actuator is well

stressed, without movement interference, and the

structure is reasonable.

3.2 Stress Analysis of the Actuator at

the end of Citrus Picking

Use ansys and Hyperworks for stress analysis. In

order to obtain more accurate data, the grid of the fruit

stem and blade is densified, and the tension on the

connecting frame is set to 150N. As shown in Table 3,

the material properties of the blade, fruit stem and

connecting rod are set, and the corresponding stress

and strain are obtained after solving.

The stress and strain nephogram of the connecting

rod and tool holder made of steel is shown in a in

Figure 7a. It can be clearly seen that the maximum

stress of the tool holder is 4.354MPa and the

maximum strain is 1.79×10

-5

；The maximum stress

of the rotary connecting rod is 7.483MPa, and the

maximum strain is 3.089×10

-5

；The maximum stress

of the connecting frame is 7.472MPa, and the

maximum strain is 3.084×10

-5

；The maximum stress

of push pull rotary connecting rod is 6.262MPa, and

the maximum strain is 2.584×10

-5

；Therefore, the

maximum stress of the whole actuator frame is

7.483MPa, and the maximum strain is 3.089×10

-5

which is far less than the yield strength of steel from

200MPa to 400MPa. In order to reduce cost and

lightweight, the alternative verification of pla material

with yield strength of 48MPa is shown in Figure 6b.

Design and Simulation of Adsorption Citrus Picking Actuator

Tool holder stress and strain

Stress and strain of rotary link

Stress and strain of push-pull rotary connecting rod

(a) steel products (b) pla products

Figure 7: Key parts stress and strain.

The analysis of the stress and strain nephogram of the

mechanism made of pla material shows that the

maximum stress on the tool holder is 23.10MPa, and

the maximum strain is 9.532×10

-5

, according to the

yield strength of the pla material, the safety factor

n=1.5 is selected, and the following is calculated:

a48a32

a10.23

smax

MPMPMP ＜＜ ==

Therefore, the tool holder uses pla material.

Similarly, the strength of rotary connecting rod, shell,

push-pull rotary connecting rod and other parts meet

the design requirements. Pla material can be used

instead of steel.

4 CONCLUSION

According to the requirements of non-destructive

picking and the basic physical characteristics of

ancient red tangerine, an adsorption type end effector

for non-destructive picking of ancient red tangerine

was designed and simulated and optimized using

finite element method. The prototype manufacturing

of the adsorbed ancient red orange non-destructive

picking end actuator was completed, and the

adsorption performance and shear performance of the

prototype were verified. The non-destructive picking

function of the adsorbed ancient red orange picking

end actuator was realized, which provided conditions

for the subsequent overall assembly test of the

intelligent orange picking robot.

ICDPCS 2023 - The International Conference on Data Processing, Control and Simulation

ACKNOWLEDGMENTS

This work is supported by Chongqing Artificial

Intelligence+Intelligent Agriculture Discipline Group

Open Fund Project (ZNNYKFB201906), Science and

Technology Research Program of Chongqing

Municipal Education Commission (KJZD-

K201901202, KJQN202101225).

CONFLICTS OF INTEREST

The authors confirm there is no conflict of interest.

REFERENCES

Zhang Yiwei, Luo Qiang, Wang Haibao, Qian Lixia. Analysis

of Citrus mechanized picking in Chongqing. Guangxi

Agricultural Mechanization, 2019 (06): 14

He Jiacheng, Wang Yang, Liu Hongbo, et al. Design of

portable orchard picker. Research on agricultural

mechanization, 2018, 40 (5): 83-87

Li Qinchuan, Hu Ting, Wu Chuanyu, Hu Xudong, Ying

Yibin. Summary of research on end effector of fruit

and vegetable picking robot. Journal of Agricultural

Machinery, 2008 (03): 175.179 + 186.

Baeten J, K Donné, Boedrij S, et al. Autonomous fruit

picking machine: A robotic apple harvester// Field and

Service Robotics. Springer, 2008.

Monta M, Kondo N, Ting K C . End-Effectors for Tomato

Harvesting Robot. Springer Netherlands, 1998.

Han Shukui, Zhao Zikai, Zhang He, Zhou Yuan, Wang

Zhenying. Design and simulation analysis of end

effector of circular citrus picking robot. Mechanical

Design, 2019, 36 (S2): 82.85.

Liu Y, Gao G.H, Wang H, Qin Y.N, Lian M.J.Innovative

Design and Simulation of a Four.Wire Flexible

Manipulator. Advanced Materials Research, 2014.

Xu Liming et al. 2018. Design and test of end effector of

navel orange picking robot. Journal of Agricultural

Engineering, 34(12):53.6.

Yang Wenliang, Feng Hu, Han Yali, Xu Youfeng.

Development of end effector of spherical fruit picking

robot driven by air pressure. Research on Agricultural

Mechanization, 2019, 41(11):149.154.

Zeng Wen, Li Kangzhen, Liu Tianhu, Xia Hongmei. Design

of end effector for citrus combing and shearing.

Forestry Machinery and Woodworking Equipment,

2019,47(09):9.13.

Kondo Zhi. Agricultural Robot. China Agricultural

University Press, 2009.

Fu Shun. Design and Research on End Effector of Citrus

Picking Robot. Chongqing University of Technology,

2017.

Wu Jijun. Design and Grasping Characteristics of End

Effector of Picking Robot. Tianjin Agricultural

University, 2018.

Design and Simulation of Adsorption Citrus Picking Actuator